Ethylene-regulated immature fruit abscission is associated with higher expression of CoACO genes in Camellia oleifera

Abstract

Immature fruit abscission is a key limiting factor in Camellia oleifera Abel. ( C. oleifera ) yield. Ethylene is considered to be an important phytohormone in regulating fruit abscission. However, the molecular mechanism of ethylene in regulating fruit abscission in C. oleifera has not yet been studied. Here, we found that the 1-aminocyclopropane-1-carboxylic acid (ACC) content was significantly increased in the abscission zones (AZs) of abnormal fruits (AF) which were about to abscise when compared with normal fruits (NF) in C. oleifera ‘Huashuo’. Furthermore, exogenous ethephon treatment stimulated fruit abscission. The cumulative rates of fruit abscission in ethephon-treated fruits (ETH-F) on the 4th (35.0%), 8th (48.7%) and 16th (57.7%) days after treatment (DAT) were significantly higher than the control. The ACC content and 1-aminocyclopropane-1-carboxylate oxidase (ACO) activity in AZs of ETH-F were also significantly increased when compared with NF on the 4th and 8th DAT. CoACO1 and CoACO2 were isolated in C. oleifera for the first time. The expressions of CoACO1 and CoACO2 were considerably upregulated in AZs of AF and ETH-F. This study suggested that ethylene played an important role in immature fruit abscission of C. oleifera and the two CoACOs were the critical genes involved in ethylene's regulatory role.

Physiological and Transcriptional Analysis Reveals the Response Mechanism of Camellia vietnamensis Huang to Drought Stress

“…Camellia vietnamensis Huang ( C. vietnamensis ), belonging to the genus Camellia in the Theaceae family, is a woody oil tree species growing in southern China [ 5 ]. The oil extracted from the seeds of C. vietnamensis is called Camellia spp.…”

Transcriptome and targeted hormone metabolome reveal the molecular mechanisms of flower abscission in camellia

“…This is the first in-depth investigation of the process of abscission in camellias focusing on flower and fruit abscission ( Wei et al., 2017 ; Hu et al., 2021 ; Zhang et al., 2022 ). Our approach enables us to investigate not only the genes involved in the molecular processes of abscission (in the receptacle) but also the potential causes of abscission.…”

Enhancing the accumulation of linoleic acid and α-linolenic acid through the pre-harvest ethylene treatment in Camellia oleifera

“…The separated shells were divided into two sections. One was fixed in 2.5% (v/v) glutaraldehyde solution for scanning electron microscopy (SEM) as previously described (Hu et al, 2021). The other was frozen in liquid nitrogen and stored at −80°C for RNA extraction.…”

“…Ethylene is involved in the regulation of multiple biological processes, such as fruit ripening, flower and leaf senescence, and fruit abscission (Vandenbussche et al, 2012;Zhou et al, 2015;Xin et al, 2019). Ethephon (2-chloroethylphosphonic acid), an ethylene-releasing molecule, is widely used as an artificial ripening agent in many fruit crops (Hu et al, 2021). For example, external application of ethephon has been proposed to increase ripening rate and facilitate early harvesting in date fruits (Phoenix dactylifera L.) (Al-Saif et al, 2017).…”